Studies will be carried out using a clonal line of rat pheochromocytoma cells (designated PC12) to study the mechanism of action and role in development of the nerve growth factor protein (NGF). In particular, we will study: 1) the roles of RNA synthesis, and 2) the role and mechanisms of regulation of microtubule assembly during NGF-stimulated neurite generation and regeneration. Proteins whose syntheses are selectively stimulated by NGF will also be characterized and assessed for their roles in neurite outgrowth.